View Full Version : Vibration/rattle in my videos
Well, ever since I first aired my camera ship, I've had a bit of a rattle/vibration showing up. The good news is I've put great efforts into detailing my heli to eliminate them. The bad news is I currently think it's not the heli at all...but a loose belt on the 'tilt' mechanism of my camera mount. It will rotate back and fort just a touch and sounds eerily similar to what my camera is picking up.
Unfortunately the system is at its current limits for tensioning the belt - need to elongate the mounting holes. Will find out tomorrow if that was the cause.
Or perhaps I'll just use velcro or something to tension the belt and make sure that's the problem, first.
T
AZ ChopperCam
10-17-2006, 10:02 PM
even if the belt is loose the camera shouldn't tilt along it's pitch axis in the gimbal unless an outside force is causing the motion.
I've run the belts on my gimbals loose and tight to test the differences and have not seen a noticeable difference between them
can you post up some video? I've seen all sorts of variations of vibes along the way over the past year. Maybe I can help you figure out what the problem is
Well, the outside force is the change in cyclic pitch.
At any rate, you've got PM. I left the spoolup in the video in case you spot something abnormal there.
AZ ChopperCam
10-17-2006, 10:39 PM
ok.. got the PM and saw the video. I do see a distinct "up/down" pitch oscillation. This is a vibe I have not seen before and you may be right in that the belt tension is not tight enought. Try flipping the HPDE blocks that the gimbal pivots on. In some cases they are not drilled perfectly centered and flipping them around will allow for tighter belt tension.
If that doesn't do it you could either elongate the holes for the servo 1/16" or go with a 144 tooth belt instead of the 146, but I'd flip the HDPE blocks first.
If that doesnt do it I will order a 144 tooth belt and have one sent to you ASAP.
Problem would appear resolved. Unfortunately I used a shotgun troubleshooting approach so I'm not sure where the problem lies.
All I know is that this was the old:
http://www.magsairsoft.com/da_shakes.wmv
After that I:
1 - replaced gohbee rotating assy with my raptor's rotating assy (gears, mast, and everything above the swash)
2 - finished rigging the camera mount - shouldn't be this but previously I had the tilt servo with insufficient tension and had simply locked the pan swivel in place. Both are now set up "properly"
3 - frankly I've forgotten what else I did now...but i know I changed something else while I was at it...
The "after":
http://www.magsairsoft.com/Movie_0003.wmv
(Note in both cases the "wild" pitching is due to the fact that I am in fact feeding full cyclic in attempts to produce the shakes. The second video, however, is flown with lightweight paddles)
AZ ChopperCam
10-19-2006, 11:11 PM
much much better.
now put in some soft black dampers, flybar wieghts and heavy paddles and you'll be shooting super smooth video.
keep posting your videos!
Definitely on the softer dampers and heavier paddles/weights. I also need to decide on either the kasama head (which I'd like to do) or just swapping the metal grips on (this was with the better of the two TT metal heads).
By the way, no need for the 144 tooth belt. Turns out the servo mount had slipped a bit and there was enough room there to tighten the belt.
Wonder if it might be worth an HDPE block in the swivel portion. Looks like I cracked the CF there overtightening it when I flipped it over (now back to normal) trying to clearance the gohbee flybar. Not needed when hooked up conventionally but I think that area is more likley to be stressed when the mount is moved below. Probably need to talk to you or Askman about replacing the cracked piece...the piece with the top swivel bearing.
AZ ChopperCam
10-19-2006, 11:42 PM
yep... I have since added a spacer tube between the pan bearings. Only the last few mounts that have went out have them. It is a wise idea. I just used nylon spacer that was wide enough to be a press in fit between the bearings.
askman
10-20-2006, 11:42 AM
sounds like I need to beef that area up a bit more. :) pm me with your address and send me a picture of the crack. want to see how it failed.
Straight stress crack.
I was trying to use a Gohbee head which has the flybar below the main rotors. This would have allowed, in reasonably extreme circumstances, the paddle to whack the servo and/or pulley.
To avoid that, DJ suggested hanging the pulley/servo underneath. When I put them on the bottom, I apparently overtightened the locknut resulting in a stress crack front-to-back through the bearing hole.
Being CF, it's still strong enough to fly for now, but I'll get a PM your way.
T